


You who swallowed a falling star

by Utuinen



Category: Kingdom Hearts
Genre: Alternate Universe - Howl's Moving Castle, Demon Deals, Established Relationship, M/M, Magic, Making Out, Minor Violence, Wizards, kinda Sea Salt Family dynamics
Language: English
Status: Completed
Published: 2020-01-28
Updated: 2020-01-28
Packaged: 2021-02-27 08:08:01
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,624
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22453906
Author URL: https://archiveofourown.org/users/Utuinen/pseuds/Utuinen
Summary: It's been ten years since Isa made a pact with a falling star for more power. In a world where wizards hunt each other to increase their own magic, being strong is truly a double-edged sword. The stronger you are, the more likely it is someone is going to come specifically after you. But the stronger you are, the more likely you are to survive it.Isa lives with his fire demon partner and the two kids he dragged in one day. He isnothaving a good day.
Relationships: Isa/Lea (Kingdom Hearts)
Comments: 10
Kudos: 61





	You who swallowed a falling star

**Author's Note:**

> I don't know when I came up with this, I simply found a note on my desk saying "Howl's Moving Castle au with Isa as Howl and Lea as Calcifer", decided the past me was onto something and started writing this.

_You who swallowed a falling star_

_O heartless man_

_Your heart will soon belong to me_

* * *

Isa woke up with a headache.

The scene from almost ten years ago was vivid in his mind. The dark field he had been standing on, craning his neck up to see the sky. The lights dashing across it, racing each other towards their end with clear voices full of laughter. The way he frowned as he had held his hand up to make one of the falling stars land on it. The mischievous smile he had seen flickering on Lea’s face for just a second after having stated all his terms, and then the feeling that had spread all across his body when the heat had engulfed him. Or he had engulfed it.

Isa rose from the bed and gathered his hair in a high ponytail, out of the way. Then he dressed, painstakingly buttoning every single button on his robe-like coat. It didn’t matter how he was feeling, he wouldn’t allow it to show on his appearance. Or, as one might also be inclined to say, the way he normally looked was no different from how he looked while he was in pain and annoyed after a night of restless sleep.

As he walked downstairs, he could hear the clatter of dishes and the sound of a cheerful conversation coming from the kitchen. It immediately stopped as he appeared in the doorway, two teens raising their heads from their breakfast to look at him.

”You’re awake! That’s... unusual,” Xion looked mostly surprised. Roxas remained silent. It was hardly surprising if he didn’t quite trust Isa—after all, Isa had given the two of them no reason to like him or trust him, even though he didn’t know what Lea had told them about him—but what _was_ was that while he still looked resenting, it wasn’t the kind of grudging look that made Isa think Roxas believed he was going to harm them. It was like Isa had just interrupted their otherwise pleasant morning with his sour appearance.

”I have some business to attend to. Take care of any customers while I’m away. If you’re not confident in your abilities, do not try anyway and mess up. Ask them to leave me a note,” Isa said, walking over to the hearth and placing the big, black kettle above the fire. He didn’t really even need to think about it before the scent of strong coffee wafted up to his nose.

”We’d be much more confident if you bothered to teach us,” Roxas muttered under his breath. Xion elbowed him hard to his side but Isa pretended he didn’t hear.

Isa drank his coffee standing and left his mug on the counter. He walked over to a curtain separating the space he used for stocking the ingredients and in some cases the finished potions and salves. He gathered what he believed he would need today, placing them neatly inside his satchel. At the door he threw a magicked cloak around his shoulders and said quietly at the space behind him: ”Keep the house standing.”

The fire in the hearth sparked, as if in answer to him.

Outside the door Isa had chosen to step out of it was a beautiful, sunny day. Seagulls glided across the sky and screeched at the busy people below them, hurrying in their own directions each. None of them looked twice at Isa, who moved through the crowd with a confident stride. Not unseen, no, more like simply _unnoticed_.

In a world where wizards hunt each other to increase their own magic, being strong was truly a double-edged sword. The stronger you were, the more likely it was someone was going to come specifically after you. But the stronger you were, the more likely you were to survive it. If you were weak, however, that didn’t mean you were safe. That just meant there was usually not much more to do than lie down and allow the other to kill you if you were caught. That was why for young, inexperienced wizards like Roxas and Xion attracting as little unnecessary attention as possible was their lifeblood.

Isa wasn’t particularly weak, but neither was he strong enough that he didn’t need to care and he could go flaunting his existence. He had fake names and addresses in multiple cities, and he was ready to abandon any one of them if they became compromised. All his clients understood the wizards’ need of secrecy, but you never knew when the word of his living place reached the wrong ears.

* * *

The sun hung low over the city when Isa made his way back home. The hustle had almost quieted and most of the street vendors were backing their tables, ready to come back tomorrow morning. The rest of them looked at the few passing people full of hope.

”Hey, mister! How about some sea salt caramels to take home for the kids? They’re sure to love them as much as seeing pa after a long day. Or if ya haven’t got any, I’m sure the missus would like them, too!” one of the vendors called out to him. ”Made locally and I can guarantee they’re delicious!”

Isa didn’t know what made him slow his steps and consider. He didn’t have _a missus_. He—technically—didn’t have kids either. And he sure didn’t expect Roxas and Xion to like the sweets if offered by him, though he was fairly certain Lea would. In the end, he bought a box and the vendor beamed at him.

Just as he stuffed the candies into his satchel, someone ran up to him with winded breath. ”You’re— the diviner Saix, right?”

Isa tensed immediately. It was rarely good if people recognized him.

”You— have to come— with great haste!” the man huffed, completely unaffected by Isa’s deep frown. ”We have employed you in the past, and our Lady has been very pleased with you, but she has fallen gravely ill! Please come and take a look at her!”

Isa hesitated. He was almost sure he _did_ recognize the page, but it was still an unusual request and there was something... off about it. Then again, sudden illnesses were often the result of curses, and if the family didn’t know any other magicians, the situation for them was likely hopeless.

He sighed and eventually told the page to lead the way.

They arrived at a grand house with big, grand halls and plenty of servants that looked worried sick. They looked at Isa with mixed faces of reverence and distrust as he hurried behind the page, up the stairs and down another hall.

”The Lady is resting here,” the page said as he stopped in front of one of the embellished doors. He knocked, and when they got a weak reply, waved Isa in.

The room was dimly lit, with heavy curtains that blocked most of the big windows reaching for the ceiling. There was a single bed, with plenty of plump cushions and silken sheets. An old, frail woman had been propped up to sit against the cushions and looked at Isa with lifeless eyes when he came closer.

The room was heavy with a dark presence which confirmed to Isa he had been right and the woman’s sickness was the work of another wizard. ”I’m here to take a look at your condition,” he said and sat next to the bed. The woman nodded languidly.

Isa took several herbs and a bottle of salve with a bitter smell from his satchel, placing them on the bedside table ready for use. He reached over the woman to check her pupils and her pulse, to try and figure out what kind of curse was affecting her.

Suddenly fingers like long, shadowy claws reached for his chest, their movement anything but listless.

”Heart, heart... finally, your heart...” the lady rasped, at first with an eerily human voice. The fingers stung at Isa’s chest, breaking the skin and clawing at him. No red spread across his chest, no blood stained the front of his coat. But it hurt. As its claws kept grasping at nothing, the ”lady” turned to high pitched wailing, its face distorting into a blank shadow. ”Heart! Your heart! Where, where?”

Isa flashed a mirthless smile, taking hold of the creature’s wrist and forcefully twisting it away. He felt the sharp drag of the claws in their final attempt to grab at him, but he was certainly stronger than the body this Shadow was using. There was an ugly cracking sound from somewhere around its elbow and the hand fell numb.

”One might almost think,” he said, ”that you should have already learned _I don’t keep it with me_.”

The Shadow’s screaming was unintelligible now, and it would have sounded like the creature was in a lot of pain if Isa hadn’t known they couldn’t feel anything. He almost hoped they could, because it would have been only fair if it hurt like he did. Isa got up as quickly as he could while the Shadow was still in a mindless frenzy and tried to make for to the door, but two other Shadows stepped out of the deep shadows near the walls, in their real forms and not hiding inside human bodies. They were _much_ stronger in their true forms. His route was cut off.

”Eat... eat, your heart...” the creatures said with one voice echoing from the walls.

Isa did not dare to even blink so as not to set them off while he tried to decide the best way out of the situation. He held the gaping, bloodless wound at his chest with one hand. There was nothing inside his rib-cage, had not been for the past ten years, and normally the only hindrance from the injury would have been the pain it caused, but right now he could feel the dark tendrils of forbidden magic slithering into his system, obstructing the flow of his own magic and preventing him from healing himself. He wouldn’t be standing much longer, much less fighting all three of them head-on, as the third was quickly shedding its human skin. He had been careless.

One of the Shadows lunged forward and Isa stumbled backwards, throwing out a near-powerless binding spell he knew wouldn’t hold the creature for long. He could almost feel at his outstretched fingertips the strands of magic snapping, one by one, as the creature inched closer with its shadow limbs.

”Show, show us, your heart...”

Isa took a deep breath.

There was one thing he could do, and he might even survive if he timed it right, but in his current state, well, it would certainly exert his remaining strength to its fullest. He would have one shot at it, and if it wasn’t enough he would be dead.

He waited until all three of the Shadows prowled against the weak bindings of his spell and then let it go altogether before it could dissipate on its own. In mere moments they were all over him, grabbing at whichever bodypart they could get hold of. At the same time, Isa released all the magic he had left in one violent burst. But the damage was not done by _his_ magic, the warm, almost frighteningly hot feel of raw magic coursing through his veins burning away the shadow tendrils and catching fire to the three Shadows touching him. His eyes glowed deep golden and his mind felt light, his body moving without him giving it direction.

As if from far away, he could hear yelling. The first voice must have been his, as it was soon joined by others that were even more distant and might have been saying something like ”Lady! Our Lady has been murdered by the magician!”

Oh please. She had been dead for a long time.

The world turned white, and Isa could remember nothing more.

* * *

When he came to, Isa was utterly tired. He was swaying on his feet at the entrance of his house, the door closed firmly behind him, the cool and smooth wood bulwark in its fixture against his back. His coat was ruined and the magic cloak was nowhere to be seen, his hair falling in strands in front of his face. The satchel had been discarded at his feet. He took a strenuous breath and made himself rise the few steps up into the main space of the house.

The house was dark, the only light coming from the hearth as a dim, golden glow. It illuminated the room just enough so that Isa didn’t trip on Roxas and Xion, who had spread their beds in the middle of the floor as they usually did, both of them fast asleep under heavy blankets. Isa looked at their sleeping figures with great difficulty to focus, and wondered if it was already time he made the two of them their own rooms. A better part of the year had already passed after Lea had invited them in from aimlessly wandering the Badlands, after all.

Isa’s knees buckled under him and he would have hit the floor hard if not for a pair of warm, familiar hands catching him and supporting his body against the other man who had probably not been standing there a moment earlier, but whose presence in the house was ever-present. Isa could hear the sound of his own heart thumping inside the man’s chest.

”What happened? You used quite a bit of my powers today,” Lea asked and looked down at Isa with genuine worry on his face.

”Xehanort’s Shadows found me,” Isa said tiredly. ”Destroy the door I used... and keep us better hidden for the next few days.”

Lea sighed and shook his head. ”Again? You’d think there are others he could go after, both stronger and weaker than us.”

”I don’t think he discriminates. He seems pretty determined to get everyone with even a hint of magic,” Isa said plainly. Usually those who killed others for the power had a stopping point, a goal after they reached they didn’t need any more. Xehanort was the first one Isa knew of that seemed completely insatiable. Maybe his goal was to become the _only_ human with magic. ”Also, don’t let the children out for now.”

”Have you started to care for them?” Lea asked with a cheeky smile as he began slowly helping Isa up the stairs, trying to keep his hold of the man as comfortable as possible.

Normally Isa might have shot him an annoyed look, but right now only his brows knitted slightly closer to each other on his otherwise expressionless face. ”You care.”

”You would too, if you let yourself. They’re good kids,” Lea said without looking down. Isa closed his green eyes and stayed quiet.

Back when he and Lea had made their pact, he had at first protested Lea taking his physical form so often. Being a fire demon, Isa had assumed he would stay in his incorporeal form. He had not expected for the deal to basically mean he would be living with someone else. Lea had smiled and pointed out that Isa had never specified in the terms of their agreement that Lea couldn’t spend most of his time looking like a human, and so he was damn sure going to. Apparently sitting around being sentient fire was boring.

At first, neither had cared about the other apart from what they could get from them. That hadn’t lasted, though, and with time they grew only closer. Isa wasn’t sure that meant he needed to accept everyone in his life who just so happened to stumble into it. And he had chosen Lea. Sure, he hadn’t fully known what would become of it, but it had still been his choice. Roxas and Xion had simply appeared in his house one day, and Isa’s opinion was never asked.

Lea nudged open the bathroom door with his leg, not kicking it so that the resulting bang wouldn’t wake the teens downstairs. He sat Isa down on a chair and ran him a medical bath while Isa struggled with his buttons to get the coat off. Lea wouldn’t have cared about doing it so neatly—it was already ruined either way. When Isa was finally bare chested and Lea could fully see the wound, he frowned. Using Lea’s powers should have already healed him somewhat but it still looked bad. Isa had a big scar on his face from previous run-ins with the Shadows, and this might well leave another.

Once the tub was full, Isa slipped into the water carefully. He rested his head back, letting out a tired sigh.

”Is the water fine?” Lea asked.

”Could be hotter,” Isa answered and followed with his eyes as Lea sat on the edge of the bathtub, leaned closer and ran his hand across the water’s surface which started steaming in its wake. The warmth was gentle and familiar, not at all scalding. Isa remembered how he had been boiled bright red all over after the first time he had dared to complain about water temperature, and even though Lea insisted it hadn’t been on purpose, he had his doubts.

Isa reached his hand out and absentmindedly carded his fingers through the red locks of hair. In the middle of doing that he closed his hand into a fist and tugged, gently enough, pulling Lea down for a kiss. Lea smiled and shifted closer, so that Isa didn’t have to crane his neck so much.

Lea was warm. Lea was always warm. The heat from his fingers as he caressed Isa’s cheek pulled him closer, the huff of his breath against Isa’s mouth when they drew back enough to catch their breath a little a welcome distraction from the pain in his chest. Isa looked at Lea with hooded eyes, and he wasn’t sure how he felt such fondness without a heart. So he just pressed against Lea again, his lips hungrily parted. Lea’s tongue brushed against them, then past them, and Isa let out another deep sigh.

When Lea pulled apart, Isa had to suppress a needy whine. He recognized the look in Lea’s eyes that meant more was coming, and besides, between the two of them he wasn’t the one who would beg for attention. Lea placed his fingers lightly on Isa’s chin and turned his head to face away, to better bare his neck. He leaned in and first kissed the skin right below Isa’s ear, exactly where the blue-green stone of Isa’s dangling earrings would have been if he hadn’t removed them and placed them on the corner of the wash-basin earlier. A lick to his ear made Isa gasp, and when Lea’s other hand simultaneously fondled at the hair just above the nape of his neck the sound turned into a soft moan. He could _feel_ Lea’s complacent smirk against his skin.

”Full of yourself, aren’t you?” Isa asked without any real bite.

”Oh, I am. Don’t worry, once you’re better I’ll make sure you are, too,” Lea chuckled in a low purr. Red flushed to Isa’s face and it had nothing to do with the water temperature. He might have turned to scowl at Lea, but Lea kept his head gently yet firmly to the side and continued kissing down his neck, each of them slow and loving. Soon Isa melted back into the touch and his eyes shuttered closed. Lea was being more careful than usual. Normally Isa didn’t like being treated as if he were fragile, but in his current state he agreed it was probably better. And it felt nice.

After the bath Lea helped Isa to his bed and tucked him in. He ran his hand through Isa’s soggy hair until it was dry and Isa had fallen unconscious.

* * *

Isa slept solidly through the next couple of days. Lea made sure both Xion and Roxas didn’t make too much noise and let him rest, though they were getting increasingly more restless when they weren’t even allowed out.

When Isa finally woke up, Lea helped him into a loose sleeved white shirt, and Isa must have really felt awful, because he didn’t argue about his appearance even once. He sat silently at the table and allowed Lea to get his coffee for him, while both Roxas and Xion quietly eyed them. Neither of them had ever seen Isa in such a state and didn’t know what to make of it.

”I’ve been thinking,” Isa started, voice hoarse from lack of use.

”I thought you’ve been sleeping,” Lea said.

A slight crease appeared between Isa’s brows but he didn’t say anything about Lea’s comment. ”We could maybe change the house around a bit. Do you two have any wishes for your own rooms? And... there’s something in my satchel for you.”

Xion got excited about the prospect of having her own room, Roxas looked like he was certain Isa had been swapped with someone else while he slept. Isa drank his coffee, not failing to notice the surprised but happy look on Lea’s face.

Isa closed his eyes and pondered. The next step was probably properly teaching Xion and Roxas magic, it was not like they could suddenly stop having their abilities if he didn’t. The better he taught them, the better changes they had to survive. He opened his eyes and looked at the teens again, now munching on the caramels Lea had retrieved from the storage he had put the satchel away on. He didn’t particularly care for them. But something told him Lea was right, and he would—if he allowed himself to.

**Author's Note:**

> If you reached here, thank you so much for reading! ♥
> 
> I would love to hear any comments or thoughts!


End file.
